internal/lsp: fix error in CL 242457
internal/lsp: fix error in CL 242457

I didn't properly understand Heschi's comment, and missed a case where
we failed to return early.

Change-Id: I692c26678b2e659c6b748085bb4b16090e04472d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/243117
Run-TryBot: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools